Original information from where this document has been obtained can be found in the man pages about diald, diald-examples, diald-control, diald-monitor, dctrl, pppd, chat, as well as from information in the /usr/doc directories and in web pages of this packages:

There is a mailing list for discussion about diald on David S. Miller's mailing list server at vger.rutgers.edu. To subscribe, send a message to Majordomo@vger.rutgers.edu with the text «subscribe linux-diald» IN THE MESSAGE BODY.

There are also multiple RFC documents (Request For Comments) that define how the PPP encapsulated lines and its associated protocols (LCP, IPCP, PAP, CHAP, ...) must work. You can find these documents in the /usr/doc/doc-rfc directory and some World Wide Web sites, like http://metalab.unc.edu and http://nic.mil/RFC. You can ask for information about RFCs in RFC-INFO@ISI.EDU.